Two stage regeneration of platinum containing catalyst composite employed in hydroforming



Oct 14, 1958 R. M. LOVE 2,

Two STAGE REGENERATION OF PLATINUM CONTAINING CATALYST COMPOSITE EMPLOYED IN HYDROFORMING Filed March 18, 1955 FURNACE 4 v a 62 4 -58 63 COOLER FURNACE k BURNERS [22 46 BURNERS 42 23., AIR

FLUE GAS -/-7 A was TER 5 REACTION 5 zones 6 4 conpnzsson CATALYST aE0sE 32 I5 J16 5;. COMPRESSOR 42 z j MAKE A, 38, 57

ans 54 IT\2-] 7 J n 27 E5 54 MAKE FLUE 30 COOLER 28 5E PARA TOR rnooucr INVENTOR. Roberf M. Lave,

A A TTOENEY.

United States Patent O TWO STAGE REGENERATION OF PLATINUM CONTAINING CATALYST COMPOSITE EM- PLOYED IN HYDROFORMING Robert M. Love, Baytown, Tern, assignor, by mesuc assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application March 18, 1953, Serial No. 343,198 6 Claims. (Cl. 208-440) The present invention is directed to a method for reconditioning a platinum hydroforming catalyst. More particularly, the invention is directed to the maintenance of activity of a platinum on alumina hydroforming catalyst. In its more specific aspects, the invention is directed to a fixed bed hydroforming operation in which naphthenic hydrocarbons are hydroformed employing a platinum catalyst.

The present invention may be briefly described as involving the conditioning of a supported platinum catalyst which has lost activity in converting hydrocarbons and/ or has become fouled with carbonaceous material and carbon in a conversion operation at a temperature in the range between 900 and 1000 F. in which hydrocarbon and hydrogen are contacted with the bed. In this particular operation, an inert gas such as flue gas is flowed over the bed of platinum catalyst at a temperature in the range between 600 and 1000 F. to purge the naphthenic hydrocarbon and hydrogen from the bed. The temperature of the flue gas is then adjusted to a temperature in the range between 700 and 800 F., and the flue gas is diluted with a free oxygen-containing gas in an amount suflicient to support a combustion operation in the bed wherein there is a flame front advancing through the bed in the direction of flow at a temperature not in excess of 1100 F. until the carbonaceous material and carbon are burned from the bed. The free oxygen content of the flue gas is then increased to a partial pressure of at least one atmosphere while the temperature of the flue gas is increased to a temperature between 1050 and 1100 F.

This free oxygen-containing gas is then cooled to a temperature in the range between 800 and 900 F., and the flow of the free oxygen-containing gas is continued until the bed has been cooled to a temperature in the range between 800 and 900 F. The flow of the free oxygen-containing gas is then terminated, and flue gas is flowed over the bed at a temperature in the range between 800 and 900 F. to remove free oxygen from the bed. Then a free hydrogen-containing gas is flowed over the bed at a temperature in the range between 800 and 900 F., and the temperature of the bed is then increased to a temperature in the range between 900 and 1000 P. which is reaction temperature wherein a conversion operation is conducted by introducing into contact with the bed a naphthenic hydrocarbon boiling in the range between 150 and 500 F.

In the practice of the present invention, the hydroforming operation is conducted at a temperature in the range from about 900 to 1000 F. Desirable results are obtained at about 950 F. The regeneration operation is conducted at a temperature in the range from 1050 to 1100 F. in a combustion operation in which non-volatile carbonaceous deposits and carbon are removed from the catalyst by burning in the presence of free oxygen.

The pressure employed in the operation preferably ranges from about 200 to about 400 p. s. i. g. but pres- "ice sures as low as 50 p. s. i. g. and as high as 700 p. s. i. g. may be used.

The amount of hydrogen employed will range from about 1000 cubic feet to about 10,000 cubic feet per barrel of feed. The preferred operation will employ about 5000 cubic feet of hydrogen per barrel of feed. While pure hydrogen may be used ordinarily, I would preferably employ a free hydrogen-containing gas.

Likewise, while I may employ air as the free oxygencontaining gas, I may suitably use other gases, such as flue gas, which has been diluted with air or free oxygen;

It is important in the present invention that the amount of free oxygen in the flue gas be increased so that the partial pressure of the oxygen is at least one atmosphere during the time that the flue gas containing the oxygen is heated to a temperature of from 1050 to 1100 F. and when the free oxygen-containing flue gas is being passed Over the catalyst bed to cool it to a temperature between 800 and 900 F. To illustrate the amounts of oxygen present in the free oxygen-containing gas the following table of data is given for varying operating pressures:

Table Percent Oxygen in Oxygen- It will be seen from these data that operating at a pressure in the range from 200 to 400 p. s. i. g. that I may use a free oxygen-containing gas containing a minimum of from about 3 /2% to 7% by volume of free oxygen.

The hydrocarbon employed as the feed stock of my invention is a naphthenic hydrocarbon boiling in the range from about to about 500 F. Such naphthenic hydrocarbons may be obtained from crude petroleums, such as the Coastal crude oils, the California type crudes and particularly those from naphthenic base crude petroleum. I may also employ as a feed stock, either alone or in admixture with the crude petroleum fractions, the naphthenic fractions boiling in the range from 150 to 500 F. obtained in catalytic conversion operations, such as catalytic cracking operations. It is preferred, however, to employ the crude petroleum fractions.

The feed stock to the present invention will ordinarily be charged to the process at a liquid space velocity in a range from about 1 to about 4 liquid volumes of feed per volume of catalyst per hour. A space velocity; of 2 v./v./hr. gives very desirable results when charging a hydrocarbon fraction from a Coastal crude.

The catalyst employed in the practice of the present invention preferably will be a platinum on alumina catalyst containing from about 0.1% to 3.0% by weight of platinum, preferably 0.2% to 1.0% by weight. It is desirable that the alumina on which the platinum is deposited be a purified alumina, such as a gamma alumina derived from boehmite. Although gamma alumina or purified alumina is preferred, I may use a platinum on alumina derived from other sources. There are numerous aluminas on the market which are available as supports for catalysts and I intend that I may use a platinum on alumina catalyst of the type available. I also intend that other supported platinum catalysts may be used such as platinum on zirconia, magnesia, and magnesiaalumina mixtures, and the like.

In the practice of the present invention the cooled catalyst may be contacted with hydrogen or with a mixture of hydrogen and hydrocarbon after purging free oxygen from the cooled catalyst. It may be desirable, for example, to contact the cooled catalyst with hydrogen and then bring the temperature of the hydrogen and catalyst mixture up to reaction temperature before the hydrocarbon is admixed therewith. Desirable results, however, are obtained by contacting the cooled catalyst with hydrogen and hydrocarbon and bringing the hydrogen-hydrocarbon mixture and the catalyst up to reaction temperature.

vThe invention will be described in more detail by reference to the drawing in which the single figure is a flow she t of a p eferre mode o practicing h invention- Refe r ng no t he dra n numerals 11 n 12 designate reaction zones in which are provided, respectively, beds 13. and 14 of a supported platinum catalyst of the type illustrated. The beds 13 and 14 are arranged in zones 11 and 12, respectively, on grid plates 15 and 16.

'In conducting my invention there is introduced into the system from a source, not shown, by way of line 17 containing pump 18, a naphthenic hydrocarbon, such as one boiling in the range from about 200 to 300 F. The naphthenic hydrocarbon is introduced into a heater or furnace 19 provided with a heating coil 20 and with burners 21. In the heater 19 the' temperature of the naphthenic hydrocarbon is raised to a temperature in the range between 900 and 1000 F. which serves to vaporize the hydrocarbon. The heated vaporized hydrocarbons leave furnace 19 by way .of line 22 and has admixed with it a free hydrogen-containing gas which is introduced by line 23 from a source which will be described further. The mixture 'of vaporized hydrocarbon and free hydrogencontaining gas discharges from line 22 into branch line 24 controlled by valve 25 into reaction zone 11 and passes downwardly therethrough and the naphthenic hydrocarbons are hydroforrned or converted to aromatic hydrocarbons, the reaction temperature in bed 11 being in the range from about 900 to about 1000 F. and preferably at an average temperature of 950 F. i The products in reaction zone 11 are withdrawn by line 26. controlled by valve 27 into line 28 and then flowed through a cooler 29 and the cooled reaction products are hen introduced into a separator zone 30 which serves to separate the liquid products from the fixed gases which include hydrogen. The liquid products are withdrawn from separator 30 by line 31 to be further separated by fractional distillation.

The fixed gas containing a substantial amount of free hydrogen is withdrawn from separator 30 by line 23 containing a compressor 32 and a heater 33, the free hydrogen-containing gas being suitably compressed and heated before introduction into line 22 as has been described.

Since there is a net production of free hydrogen in such hydroforming operations, it is necessary to withdraw a certain amount of hydrogen-containing gas from :the system. To this end I provide line 34 controlled by valve 35 for withdrawing this gas for further use as may 'be desired.

After a period of operation, such as has been described, the catalyst in reaction zone 13 loses its activity toward converting hydrocarbons to an extent it resists restoration by the burning operation and/ or becomes fouled with carbonaceous material and carbon which is deposited on the catalyst during the operation and it, therefore, becomes necessary to take the reaction zone 11 out of the reaction cycle and put it on the regeneration cycle which will be described in further detail. Since it is desired to employ a continuous operation, the heated naphthenic hydrocarbon in vaporous form in admixture with the free hydrogen-containing gas is then routed into reaction zone 12 by opening valve 36 in branch line 37 which discharges the reaction mixture downwardly through the bed 14. The reaction products issue from the bed 14 by line 38 controlled by valve 39 which then 4 routes them by line 28 through cooler 29 and into separator 30 for recovery of the product and the free hydrogen-containing gas.

It is then necessary to regenerate the catalyst or recondition it for further use while maintaining the activity of the platinum catalyst. In accordance with my invention I then purge the hydrocarbon and hydrogen which are contained in the bed 13 therefrom by flowing flue gas over the bed of catalyst at a temperature in the range between 600 and 1000 F. This is accomplished at the start of the operation by introducing through line 40 controlled by valve 41, which connects into line 42, flue gas from a source not shown. This flue gas passes through line 42 controlled by valve 43 into a heater 44 provided with heating coils 45 and burners 46 which serve to raise the temperature to within the range indicated. The heated flue gas at a temperature between 0 a d 0 0 h n pa ses ou d y f om oi 45 by way of line .47 into by-pass line 48 controlled by valve 49 and thence into line 50 and into manifold 51, valve 63 being closed. By maintaining valve 52 in the closed po n'and op ing v e 5 t u gas pa se o a d v rough the be 13 a d ou a y t efrom through line 26 and to line 54 controlled by valve 55, valve 27 being closed. The flue gas passes from line 54 to line .42 controlled by valve 42a which contains a compressor 56 which serves to raise the pressure. of the flue gas suificiently to recycle it in'the system as has been described. Since there is a net production of flue gas and since during certain periods of operations it is necessa y t di ca 'flue g hi pur o y e from h cata ys ed prov s on s m o di a ge flu gas from the system by 0Pnir1g valve 57 in line 54. The flow, a n cate hr u l s .2. 48, 50 a d man ftild 51 through bed 13, is continued until the hydrocarbon and hydro e is p d from e b d The tempera u of the flue gas islthen adjusted to a temperature in the range between 700 and 800 F. either by fldjusting'the input of heat in heater 44 or by by-passing a portion of the flue gas at a temperature in the range between 700 controlled by valve 59 and thereafter flowing the flue gas through lines 47 and 48 to line 50. The flow of the flue as at a temperature in the range between 700 and 800 F. is continued until the temperature of the bed is at a temperature between 700 and 800 F. The flue gas is then diluted with a free oxygen-containing gas, such as air, which is introduced into line 42 by line 60 controlled by valve 61 which connects to a source of compressed air. The amount of air or free oxygencontaining gas introduced into line 42 by line 60 is a suflicient amount to support a combustion operation in bed 13. Usually this amount of air which is used to dilute the flue gas is of suflicient amount to provide as much as 3% by volume of oxygen in the flue gas. Actually the factor which governs the amount of oxygen is the temperature of the advancing flame front which is in the direction of flow downwardly in bed 13 such that the temperature of the flame front does not exceed 1100 F. Ordinarily an amount of oxygen of about 2% by volume will be sufficient. The temperature of the fl-ue gas containing oxygen is maintained at about 700 to 800 F. such that the relatively cool flue gas serves to remove heat from the burning bed and maintains the temperature of the flame front not over l This operation is continued with the dilute flue gas until the carbonaceous material and carbon are burned from the catalyst in the bed. The free oxygen content of the flue gas is then increased to provide an oxygen partial pressure at least equivalent-to one atmosphere. by adding more air through line ,60 While the temperature of the flue gas is increased to a temperature in the range from 1050 to 1100 F. This is suitably done by closing valve ,59 and allowing the flue gas diluted with air to W through the heater 45 whichis adjusted tointroduce more heat to the flue gas flowing through heater 45.

After a temperature in the range between 1050 and 1100 F. has been achieved, the free oxygen-containing flue gas is cooled to a temperature in the range between 800 and 900 F. and the flow of the cooled free oxygencontaining flue gas continued over the bed until the temperature of the bed is in the range between 800 and 900 F. In this operation this may readily be achieved by closing valve 49 in by-pass line 48 and allowing the flue gas tobe routed from line 47 through cooler 62 and then by opening valve 63 in line 50 into manifold 51 and thence into bed 13. This operation is continued until the bed is at a temperature between 800 and 900 F.

The flow of free oxygen-containing gas is then terminated by closing valve 61 in line 60 and flue gas is allowed to purge the bed at a temperature between 800 and 900 F., the flow being as indicated through the cycle from line 42, heater 44, cooler 62 and thence by way of manifold 51 to bed 13 and to line 54 discharging flue gas from the system by opening valve 57 valve 42a being closed. After the bed' has been purged of free oxygen the flow of vaporized hydrocarbon and free hydrogen-containing gas mixture is resumed through line 22 and line 24 as has been described, valves 53 and 57 being closed and valve 42a being opened.

By this time the bed 14 has become fouled by carbonaceous deposits and carbon and a similar operation is conducted to recondition or regenerate the bed 14 of platinum catalyst, the flow of the flue gas and free oxygen-containing gas being from line 50 into manifold 51 and thence to zone 12, valve 52 being opened and valve 36 being closed. The combustion products issue from the reaction zone 12 by line 38 and by way of branch line 64 controlled by valve 65 into line 54 and thence to line 42, as has been described, valve 39 in line 38 being closed. Since the sequence of reconditioning steps for bed 14 is the same for bed 13, the description thereof will not be repeated.

This operation results in maintenance of activity and reconditioning of the catalyst to allow obtaining of high octane number products.

As will be clear from the foregoing description, it is specifically contemplated that the particular treatment for restoring catalyst activity need not be performed after each burning or regeneration operation but may be performed when the activity of the catalyst after regeneration has fallen to a point where the operation is unattractive. Thus I contemplate treating the regenerated catalyst when its activity toward converting hydrocarbons has decreased and such activity is not restored by the ordinary burning of carbon and carbonaceous material from the catalyst.

The invention will be illustrated by an example in which a platinum on alumina catalyst containing 0.6% by weight of platinum was employed for about 1200 hours in a fixed bed unit charging a 200 to 300 F. boiling range naphtha from a Coastal crude at a pressure of 275 p. s. i. g. and a recycle gas to feed ratio of 5000 standard cubic feet per barrel, the recycle gas containing 85% of hydrogen. The temperature in the inlet to the bed was 975 F., and the naphtha was charged at a space velocity at 2 volumes of feed per volume of catalyst per hour. During this operation a product having a 95 Research clear octane number was obtained at 83 to 84 volume percent debutanized yield.

After the catalyst had lost some of its activity and selectivity as a result of the reaction time and three regenerations with a gas containing 0.5 to 1% of oxygen, the catalyst was again regenerated and subjected to the following treatment:

Air at 290 p. s. i. absolute (about 60 p. s. i. absolute partial pressure of oxygen) was passed over the catalyst while heating the system to 1100 F. where it was maintained for 24 hours. The catalyst bed at 1100 F. was then purged with nitrogen and the temperature reduced to 950 F. Hydrogen was introduced when the catalyst had reached 950 F. and the reaction period was started by introducing the feed hydrocarbon again. After 50 hours on operation it was found that the octane number of the product had dropped to 86 with a debutanized yield of 81 volume percent as compared to a yield with fresh catalyst at this octane level of 91 volume percent.

Thereafter the present invention was employed, the catalyst being regenerated by burning with 0.5 to 1% oxygen. In my invention oxygen at 35 to 45 p. s. i. absolute was passed over the catalyst while it was heated to 1100 F., and this temperature was held for 24 hours. The catalyst was then cooled to 800 F. while continuing the flow of oxygen over the catalyst. At 800 F. the oxygen was purged from the catalyst with nitrogen, and hydrogen flow was initiated. After the initiation of hydrogen flow the catalyst was heated to reaction temperature to 950 F. in the presence of hydrogen and the reaction was begun by introducing the naphthenic hydrocarbon feed. At standard operating conditions including an average temperature of 930 F., a pressure of 275 p. s. i. g. and a space velocity of 2.0 v./v./hr. a prodduct Research clear octane number of 97 was obtained at a debutanized yield of 82 volume percent. This compares with the Research clear octane number and the 83 to 84 volume percent yield based on the debutanized product obtained initially. These excellent results were maintained for 400 hours with substantially no change.

It will be seen from the foregoing comparison that I obtained unexpectedly superior results by my conditioning treatment and furthermore that a catalyst whose activity had depreciated is reconditioned so that its initial activity is restored. Furthermore by the practice of my invention the activity of the catalyst may be maintained.

While the invention has been described and illustrated by reference to flue gas as the inert gas, other inert gases, such as pure nitrogen, carbon dioxide, and mixtures thereof, may be used.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. A method for conditioning a fixed bed of supported platinum on purified alumina catalyst which has lost activity and has become fouled with carbonaceous material and carbon in a conversion operation at a temperature in the range between 900 and 1000 F. in which naphthenic hydrocarbon and hydrogen are contacted with said bed which comprises flowing an inert gas over the bed of catalyst at a temperature in the range between 600 and 1000 F. to purge said naphthenic hydrocarbon and hydrogen from said bed, adjusting the temperature of the inert gas to a temperature in the range between 700 and 800 F. and continuing to flow inert gas over said bed until the temperature of the bed is in the range between 700 F. and 800 F., diluting the inert gas with a free oxygen-containing gas in an amount sufiicient to provide an oxygen partial pressure of less than one atmosphere and to support a combustion operation in said bed having a flame front advancing through said bed in the direction of flow at a temperature between that of the bed after flow of said inert gas thereover and before the combustion operation and a temperature not in excess of 1100 F. until said carbonaceous material and carbon are burned from the bed, increasing the free oxygen content of the inert gas to provide a partial pressure of at least one atmosphere while increasing the temperature of the inert gas to a temperature in the range between l050 and 1100 F., cooling the free oxygen-containing inert gas having the increased free oxygen content to a temperature in the range between 800 and 900 F. and continuing the flow of said cooled free oxygencontaining inert gas over said bed until the temperature of the bed is in the range between 800 and 900 F., terminating the flow of said cooled free oxygen-containing inert-gas,- removing free-oxygen' fi'em'contact with said cooled bed,-*flow inga-free hydrogen-containing gas over said bed'at a temperature in the' range' between 800 and 900 F.,and then increasingthe temperature of the'bed to a temperature inthe range between 900 and 1000 F.

'2. A method in accordance with claim 1 in which the inert gas-is flue gas.

3. Aniethod for-conditioning a fixed bed ofplatinum on purified aluminacatalyst which has lost activity and has become fouled; with carbonaceous-material and carbon in a hy'droforming operation at a temperature in the range between 900" and-1000 in'w-hich a vaporized naphthenic hydrocarbon--boiling in the range between 150-' and 500 F." and -hydrog'en' are contacted with said bed which comprises -flowingflue gas'over the bed of catalyst ata temperature i the range between 600 and 1000 F. "topurge said' ph'thenic hydrocarbon and hydrogen' fro'm said bed; adjusting the temperature of I the flue gas to a temperature in the range between 700 and 800 F. while continuing 'to-fiow flue gas' over saiclbed until the temperaturebf-the bed is' inthe range between 700 and 800 F.,'-dilutir1g the-flue gas with a'free' oxygencontaining gas in an amouhtsuflicient to' provide an oxygen partial pressure of less-than one atmosphereand to supporta combustion operation'in said bed having a flame front advancing through said bedin' the direction of flow at a temperature between that of the bed after flow of said flue" gasthe'reever and beforethe combustion operation and a temperaturenot"in excessof 1100 F. until said carbonaceous-material and carbon are burned from-the bed, increa'sing'the free oxygen content of the flue as to -provide a-' partia1 *pressure'of at least one atmosphere WhiIe inCreas'ingihetemperatureof the flue gas to a temperature in the range between 1050 and 1100 F cooling'thefree'oxygen-contaihing flue gas'having an increased "free oxygenc'ontent to a temperature in the range between-800 and 900 F. and continuing' the flow of said cooled free oxygen-containing flue gas over said bed until the temperature of thebed is in the range between800 and 900 F., te'rminating the flow of said cooled free oxygen-containing fiuegas, removing free oxygen from contact with said cooled bed, flowing a free hydrogen-containing gas'over sjaidbed at a temperature in the range between 800 and 900 F.,and then increasing the temperature of the bedto a temperature in the range between 900 and 1000 F.

4. A method in accordance with claim 3 in which the free oxygen-containing gas is air and the flue gas is diluted with a suflicient'amount of air to provide an amount of oxygen in said flue'gas no greater than 3% by volume.

5. A method for obtaining high yields of high octane number product in which -a fixed bed of platinum on purified alumina catalyst whichhas lost activity and has become fouled with"carbonaceous"material and carbon in a hydroformihgoperation at a temperature in the range between 900 and 1000 F. by contact with a vaporized naphthenic hydrocarbon boiling in the range between 150 and 500 F. and hydrogen is'conditioned to produce said yields and product which comprises flowing flue gas over said bed of catalyst-at a temperature in the range between 600 and 1000 F.'to purge said naphthenic hydrocarbon and. hydrogen from said bed, adjusting the temperature of the flue gas' to a'temperature in the range between 700 and 800 Fywhilecontinuing to flow flue gas over said bed until the temperature of the bed is in the range between 700 F. and 800 F., diluting the flue gas with a free oxygen-containing gas in an amount sufficient to provide an oxygen 'partial'pressure of less than one atmosphere and to support a combustion operation in said bed having a flame front advancing through said bed in the direction of flow at a temperature between that of the bed after flow of said flue gas thereover and before the combustion operation and a temperature not in excess of 1100 until said carbonaceous material and carbon are burned from the bed, increasing the free oxygen content of the flue gas to provide a partial pres- I sure of at least one atmosphere while increasing the temperature of the flue gas to a temperature in the range between 1050 and 1100 F., cooling the tree oxygencontaining flue gas having an increased free oxygen content to a temperature in the range between 800 and 900 F. and continuing the flow of said cooled free oxygen-containing flue gas over said bed until the temperature of the bed is in the range between 800 and 900 F., terminating the flow of said cooled free oxygencontaining flue gas, flowing flue gas over said cooled bed at a temperature in the range between 800 and 900 F. to remove free oxygen from said bed, flowing a free hydrogen-containing gas oversaidbedat a temperature in therange between 800 and 900 F.,- increasing the temperature of the bed to a temperature in the range between 900 and 1000 F., and then flowing said naphthenic hydrocarbon over said bed in admixture with said freehydrogen-containing gas to form high yields of high octane number product from said naphthenic hydrocarbon. 7

6. A method for obtaining high yields; of high octane number product in which a fixed bed of platinum on purified alumina catalyst which has lost activity and has become fouled with carbonaceous material and carbon in a hydroforming operation at a temperature in the range between 900 and- 1000" F. by contact with a vaporized naphthenic hydrocarbon boiling in the range between and 500 F. and'hydrogen is conditioned toproduce said yields andproduct which comprises flowing flue gas over said bed of catalyst at a temperature in the range between 600 and 1000 F. to purge said naphthenic hydrocarbon and hydrogen from said bed, adjusting the temperature of the flue gas to a temperature in the range between 700 and 800 F. while continuing to flow flue gas over said bed until the temperature of the bed is in the range between 700 and 800 F., diluting the flue gas with a free oxygen-containing gas in an amount sufficient to provide an oxygen partial pressure of 'less than one atmosphere and to support a combustion operation in said bed having a flame front advancing through said bed in the direction of flow at a temperature between that of the bed after flow of said flue gasthereover and before the combustion operation and a temperature not in excess of 1100 F. until said carbonaceous material and carbon are burned from the bed, increasing the free oxygen content of the flue gas to provide a partial pressure of at least one atmosphere while increasing the temperature of the flue gas to a temperature in the range between 1050 and 1100 F., cooling the free oxygen-containing 'fluegas having an increased oxygen content to a temperature in the range between 800 and 900 F. and continuing the flow of said cooled free oxygen-containing flue: gas over said bed until the temperature of the bed is in the range between 800 and 900 F.,-' terminating the flow of said cooled free oxygen-containing flue gas, flowing flue gas over said cooled bed at a temperature in the range between 800 and 900 F. to remove free oxygen from said bed, flowing a mixture of said naphthenic hydrocarbon and a free hydrogen-containing gas over said bed at a temperature in the range between 800 and 900 F., and then increasing the temperatureof the bed to a temperature in the range between 900 and 1000 F. to form high yields of high octane number product from said naphthenic hydrocarbon.

References Cited in the file ofthis patent 

5. A METHOD FOR OBTAINING HIGH YIELDS OF HIGH OCTANE NUMBER PRODUCT IN WHICH A FIXED BED OF PLATINUM ON PURIFIED ALUMINA CATALYST WHICH HAS LOST ACTIVITY AND HAS BECOME FOULED WITH CARBONACEOUS MATERIAL AND CARBON IN A HYDROFORMING OPERATION AT A TEMPERATURE IN THE RANGE BETWEEN 900* AND 1000*F. BY CONTACT WITH A VAPORIZED NAPHTHENIC HYDROCARBON BOILING IN THE RANGE BETWEEN 150* AND 500*F. AND HYDROGEN IS CONDITIONED TO PRODUCE SAID YIELDS AND PRODUCT WHICH COMPISES FLOWING FLUE GAS OVER SAID BED OF CATALYST AT A TEMPERATURE IN THE RANGE BETWEEN 600* AND 1000*F. TO PURGE SAID NAPHTHENIC HYDROCARBON AND HYDROGEN FROM SAID BED, ADJUSTING THE TEMPERATURE OF THE FLUE GAS TO A TEMPERATURE IN THE RANGE BETWEEN 700* AND 800*F. WHILE CONTINUING TO FLOW FLUE GAS OVER SAID BED UNTIL THE TEMPERATURE OF THE BED IS IN THE RANGE BETWEEN 700*F. AND 800*F., DILUTING THE FLUE GAS WITH A FREE OXYGEN-CONTAINING GAS IN AN AMOUNT SUFFICIENT TO PROVIDE AN OXYGEN PARTIAL PRESSURE OF LESS THAN ONE ATMOSPHERE AND TO SUPPORT A COMBUSTION OPERATION IN SAID BED HAVING A FLAME FRONT ADVANCING THROUGH SAID BED IN THE DIRECTION OF FLOW AT A TEMPERATURE BETWEEN THAT OF THE BED AFTER FLOW OF SAID FLUE GAS THEREOVER AND BEFORE THE COMBUSTION OPERATION AND A TEMPERATURE NOT IN EXCESS OF 1100*F. UNTIL SAID CARBONACEOUS MATERIAL AND CARBON ARE BURNED FROM THE BED, INCREASING THE FREE OXYGEN CONTENT OF THE FLUE GAS TO PROVIDE A PARTIAL PRESSURE OF AT LEAST ONE ATMOSPHERE UWHILE INCREASING THE TEMPERATURE OF THE FLUE GAS TO A TEMPERATURE IN THE RANGE BETWEN 1050* AND 1100*F., COOLING THE FREE OXYGENCONTAINING FLUE GAS HAVING AN INCREASED FREE OXYGEN CONTENT TO A TEMPERATURE IN THE RANGE BETWEEN 800* AND 900*F. AND CONTINUING THE FLOW OF SAID COOLED FREE OXYGEN-CONTAINING FLUE GAS OVER SAID BED UNTIL THE TEMPERATURE OF THE BED IS IN THE RANGE BETWEEN 800* AND 900*F., TERMINATING THE FLOW OF SAID COOLED FREE OXYGENCONTAINING FLUE GAS, FLOWING FLUE GAS OVER SAID COOLED BED AT A TEMPERATURE IN THE RANGE BETWEEN 800* AND 900*F. TO REMOVE FREE OXYGEN FROM SAID BED, FLOWING A FREE HYDROGEN-CONTAINING GAS OVER SAID BED AT A TEMPERATURE IN THE RANGE BETWEEN 800* AND 900*F., INCREASING THE TEMPERATURE OF THE BED TO A TEMPERATURE IN THE RANGE BETWEEN 900* AND 1000*F., AND THEN FLOWING SAID NAPHTHENIC HYDROCARBON OVER SAID BED IN ADMIXTURE WITH SAID FREE HYDROGEN-CONTAINING GAS TO FORM HIGH YIELDS OF HIGH OCTANE NUMBER PRODUCT FROM SAID NAPHTHENIC HYDROCARBON. 